1. Field of the Invention
The present invention relates to an apparatus and a method for controlling an iris in a video camera. More particularly, the present invention relates to an apparatus and a method for controlling an iris according to a brightness variation of an input signal to generate a video signal having a proper brightness level.
An apparatus for controlling an iris, which controls the aperture size of the iris according to the brightness variation of the input video signal in order to process a video signal having a proper brightness level, is indispensable to a video camera.
2. Description of the Prior Art
A conventional apparatus for controlling the iris of a camera uses a feedback method, and controls the aperture size of the iris when the brightness level of the input video signal changes, thereby achieving a video signal having a proper brightness level. The conventional apparatus for controlling the iris of a camera is shown in FIG. 1.
FIG. 1 is a block diagram of a conventional apparatus for controlling the iris of a camera; and FIG. 2 is a flow chart showing the operation steps of the conventional apparatus shown in FIG. 1.
As shown in FIGS. 1 and 2, a data detector 12 senses the brightness level of an input video signal input from an iris 11 (step 21). A controller 13 judges whether a change in the size of the aperture of the iris 11 is needed (step 22). If variation of the aperture size of the iris 11 is needed, the controller 13 calculates a control value of the iris 11, and outputs the control value to an iris controller 14 (step 23). The iris controller 14 controls the aperture size of the iris 11 in accordance with the control value from the controller 13 (step 24).
The above method for controlling the iris uses feedback information. The above operations are repeated until an output video signal having a proper brightness level has been achieved.
If the brightness of the input video signal is varied, control of the aperture size of the iris restarts according to the varied brightness. Therefore, time is required to adjust the iris to output a video signal having a proper brightness level. In the meantime, a video signal having improper brightness is generated until the iris has been completely adjusted.